With the increasing drilling scale of oil and gas fields and the development of science and technology, especially the rapid development of a LWD technology, it is urgent to make the present advanced science and technology play an important role in the development of the oil and gas fields. An azimuthally acoustic LWD technology is one of the LWD technology. Acoustic LWD enables acoustic logging while drilling, which can effectively detect lithological characters, physical properties and reservoir parameters of a wellbore wall formation. With the development of an acoustic LWD instrument, an acoustic quadrupole LWD instrument has been developed because it can obtain more information about the formation. The acoustic quadrupole LWD instrument is higher in requirements for transmitting and receiving transducers relative to acoustic monopole and dipole LWD instrument. Meanwhile, the acoustic quadrupole LWD instrument proposes extremely high requirements for consistency in resonant frequencies and transmitted signal strengths of the transmitting transducers and receiving sensitivity of the transmitting transducers because of taking functions of the acoustic monopole and dipole LWD instruments into account. Performance instability of the transmitting transducers and the receiving transducers under a free state and an installation state results in more difficulty in obtaining the transmitting transducers and the receiving transducers with high consistency and high sensitivity.
An acoustic source testing method of existing azimuthally acoustic LWD is to obtain key indicators such as consistency in transmitted signal strengths and resonance frequencies, and acoustic signal reception sensitivity of an acoustic source (i.e., transmitting transducers and receiving transducers) of the azimuthally acoustic LWD through an impedance analyzer and a silencer pool test during the development of the transmitting transducers and the receiving transducers. However, in an application of the azimuthally acoustic LWD instrument, when the transmitting transducers and the receiving transducers are installed on a drill collar, the transmitted signal strengths and the resonance frequencies of the transmitting transducers as well as the receiving sensitivity of the transmitting transducers are reduced, and the inconsistency is exhibited. This has caused great difficulties in the development of the azimuthally acoustic quadrupole LWD instrument.
When the transmitting transducers in the prior art are developed, the length of ceramic tiles within the transmitting transducers is increased, in order to increase transmitting powers of the transducers, and the ceramic tiles with a long-diameter ratio greater than 1:0.7 are stable in sintering and stable in resonant frequencies and signal transmission strengths, so that the consistency in the transmitted signal strengths and the resonant frequencies is deteriorated. A transmitting transducer with high consistency can be obtained only through post-screening, and in a conventional method, the resonant frequencies of the transducers can be indirectly obtained only by the impedance analyzer. On the other hand, after such the transmitting transducers and the receiving transducers are installed on the drill collar, their transmitted signal strengths and resonant frequencies are changed, so that the consistency of the individual transmitting transducers and the receiving sensitivity of the receiving transducers cannot be effectively verified.